Randomized, controlled trial comparing 3 treatment arms to determine if parenteral insulin therapy is effective in preventing clinical diabetes. The initial intervention was a pilot study started in 1988, in which 5 subjects were treated with a combination of IV insulin for 5 days every 9 months (in the GCRC), combined with twice daily injections of low dose insulin during the intervening months. The results were significant when compared to 7 controls who declined treatment. The study continues to follow the subjects to assess the significance of the finding that this type of intervention could be effective in preventing clinical diabetes and the subsequent complications, and to determine any differences between the three groups. The anticipated benefit is to possibly delay or prevent the development of Insulin Dependent Diabetes (IDDM).